In the pilot episode, Sonny
used a .45 caliber Sig-Sauer P220. During the first two
seasons, he used a stainless steel Bren 10mm manufactured by Dornhaus and Dixon (clearly seen in the "Glades" and "One Way
Ticket" episodes).

Starting with the third season, Sonny used
a stainless steel .45 caliber Smith & Wesson 645 (carried in a Galco Miami Vice Holster).

During the last season Sonny used a
Smith & Wesson model 4506. He also carried .45 caliber Detonics CombatMaster
for a backup weapon in an ankle holster on his left leg
("Prodigal Son" episode).